1. Field of the Invention
This invention relates to modifying the cross-sections of solid and surface geometry formed by an arbitrary intersecting plane or surface in an intuitive manner.
2. Prior Art
Objects in a CAD system can be represented in a parameter-based way or in a geometry-based way. In a parameter-based representation, the object is modeled as an object along with a set of features and history that define the object. In a geometry-based representation, the object is simply represented as a set of geometric data.
Most modern CAD systems offer the ability to create cross-sections. Two dimensional (2D) CAD systems (such as AUTOCAD) allow the user to draw representations of cross-sections of solid objects, but do not have 3D capabilities, and the cross-section serves only as an example of what a true cross-section would be.
Three dimensional (3D) CAD systems (such as SOLIDWORKS) are able to create and edit solids using cross-sections. However, the cross-section planes that can be used to edit solids must be those that define the faces of solid objects. For example, a solid object that have been created by extrusion, or by revolving a cross-section. No other cross section, except the one use to create the object, can be used for creating or editing purposes. The cross-sections cannot be placed in any position that intersects with the solid object. Arbitrarily oriented and positioned cross-sections can be placed through solid objects for the purpose of viewing the geometry, but the intersection of the solid with the cross-section cannot be used to modify the object unless the cross-section is coincident with the cross section that defined the geometry in the first place.